2. An animated Internal Combustion Engine Intake Stroke The engine cycle begins with the intake stroke as the piston is pulled towards the crankshaft (to the left in the figure).
3. The intake valve is open, and fuel and air are drawn past the valve and into the combustion chamber and cylinder from the intake manifold located on top of the combustion chamber. The exhaust valve is closed and the electrical contact switch is open. The fuel/air mixture is at a relatively low pressure (near atmospheric) and is colored blue in this figure. At the end of the intake stroke, the piston is located at the far left and begins to move back towards the right .